Other Headaches and Facial Pain Occipital Neuralgia , B.Todd Troost

12.6: Occipital neuralgia
The IHS description of occipital neuralgia is the following: occipital neuralgia is a paroxysmal jabbing pain in the distribution of the greater or lesser occipital nerves, accompanied by diminished sensation or dysaesthesiae in the affected area. It is commonly associated with tenderness over the nerve concerned. Diagnostic criteria are:

A. Pain is felt in the distribution of greater or lesser occipital nerves.

B. Pain is stabbing in quality although aching may persist between paroxysms.

C. The affected nerve is tender to palpation.

D. The condition is eased temporarily by local anesthetic block of the appropriate nerve.

According to the IHS, occipital neuralgia must be distinguished from the occipital referral of pain form the atlantoaxial or upper zygapophyseal joints or from tender trigger points in neck muscles or their insertion. Eagle’s stylohyoid syndrome is not sufficiently validated, however, elsewhere in this chapter, we have described Eagle’s syndrome.

Occipital Neuralgia
Three types of pain in the back of the head and neck can properly be classified as occipital neuralgia. The first and most common is the muscle contraction (tension) headache that has been previously described. It is characterized by a long standing, usually sustained, aching of low intensity. This pain is commonly bilateral but may be unilateral. It is associated with stiffness of the muscles of the neck, points of tenderness, and head tilting. The pain is modified by movement and manipulation of the neck. The skin and underlying tissues of the neck may be tender, and the pain may spread to the forehead and the area behind the eyes. The relationship of this headache to contraction of the head and neck muscles and resultant vasoconstriction has already been discussed.
A second type of occipital headache is related to migraine. This type is characterized by recurrent high-intensity pain with complete freedom from pain between attacks. The occipital neuralgia is 2---36 hours in duration and is usually unilateral at the onset, but it may spread to the opposite side. This throbbing pain is exacerbated by lying down. Rarely does it persist more than a few days. It is often associated with anorexia, nausea, and vomiting, and is occasionally preceded by visual scotomas and paresthesias of the extremities. These headaches are promptly and dramatically modified by ergotamine tartrate if the drug is given intravenously soon after onset. Procaine injection into the region of the occipital artery may also eliminate the headache. The interval between attacks and the intensity of the attacks are modified by adjustments in the patient's life situation and by reduction of nervous tension. This type of intermittent occipital neuralgia is a result of occipital and postauricular arterial dilation, and perhaps of dural arterial dilation as well. It is, in its nature and response to arterial vasoconstrictors, closely related to other types of vascular head pain classified under the general term of migraine.
A third type of occipital neuralgia is caused by organic disease at the craniocervical junction. This syndrome includes occipital or suboccipital headache, scalp pain, tenderness, paresthesia in the distribution of the second cervical dermatome, loss of normal cervical lordosis, and neurologic signs that are often mild. Causes of the syndrome include inflammation, injury, basilar impression, tumor, or pressure on the occipital nerves, upper cervical spinal roots, dorsal horns, or root ganglia. Malformation or instability of the joint space between the first and second cervical segments causes intermittent subluxation or root compression and reference of pain to the occiput, neck, and retrobulbar area. Correct diagnosis of occipital neuralgia therefore requires roentgenographic examination of the cervical spine, including lateral views in extreme extension, flexion, and neutral position, and open-mouthed and lateral views of the odontoid in extreme flexion and extension. The ability to perform computed tomographic scanning in this region has been of importance in diagnosing this type of occipital neuralgia.
Dugan et al. (1962) found several common features in the history and physical examination of patients with this third type of occipital neuralgia. Not infrequently, the patient has body asymmetry, is left-handed, or has some evidence of muscular imbalance or mild neurologic problem dating back to early childhood. With such a background, minimal trauma often antedates the head pain by several years. The patient's description of the pain often includes radicular pain or paresthesis in the distribution of the second cervical nerves, a complaint that should call attention to the atlantoaxial joint. Articular abnormalities of this joint can produce paresthesias in the paravertebral areas and in the arms or even the legs. Two types of subluxation of the atlantoaxial joint have been described by Coutts (1934). Simple atlantoaxial dislocation exists when there is slipping in parallel planes and when flexion of the neck occurs predominantly at the middle and lower cervical vertebrae. Complex atlantoaxial dislocation occurs in the presence of a separate odontoid process, and luxation is no longer parallel because the atlas slips forward and down. In such cases, there is a marked widening between the spinous processes of the first and second cervical vertebrae. The association of these disorders with inflammatory diseases of the pharynx and tonsils or with rheumatic conditions has long been noted. Transient spells of unconsciousness or bilateral blurring of vision probably result from partial occlusion of the vertebral artery associated with excessive movement of the atlantoaxial joint. Nystagmus (especially downbeating) or neurologic signs indicating intrinsic involvement of the upper cervical cord should alert the examiner to the possibility of brainstem compression at the craniocervical junction with or without anterior spinal artery involvement and associated ischemic cervical myelopathy.

Eye Pain From Occipital Neuritis (Greater Occipital Neuralgia)
Several investigators (Skillern, 1954; Knox and Mustonen, 1975; Bodé, 1979) have suggested the existence of an entity known as occipital neuritis or greater occipital neuralgia. Patients with this syndrome complain of eye pain that may begin in the occipital region and extend over the scalp to the eye. Other patients may have isolated eye pain that can be elicited by pressure at the base of the occipital condyle.
The presumed mechanism of this pain is inflammation involving the greater occipital nerve as it pierces the tendinous insertion of the splenius capitus at the base of the skull. The inflammation is believed to occur from chronic, sustained muscle contraction and resulting ischemia about the nerve. The nerve is additionally subjected to a moderate amount of torque with turning of the head. In addition to the mechanical effects of the splenius capitus, the trapezius and sternocleidomastoid muscles may undergo chronic, sustained contraction that produces ocular and occipital head pain. It is assumed that the eye pain that occurs in this syndrome is referred from the close association of the greater occipital nerve and the spinal tract of the trigeminal nerve.
Although there is little doubt that this syndrome occurs, it is not clear whether it is psychologic or organic in nature. Lieppman (1980) described his experience with 164 patients in whom he diagnosed this entity. Although he found a high cure rate after occipital subcutaneous injections of lidocaine, he also found a 50% cure rate in patients given occipital subcutaneous injections of saline. Bodé (1979) has suggested that such patients be treated with an injection of 0.5 cc of 0.5% Bupivacaine at a point midway between the occipital protuberance and the mastoid process followed by additional injections at sites of maximum tenderness as necessary since the half life of Bupivicaine is longer than that of lidocaine.
The greater occipital nerve (Figure 36.19) is a continuation of the dorsal ramus of C2 and emerges onto the scalp above an oponeurotic sling between the sternocleidomastoid and trapezius muscles (Bogduk, 1980). The nerve is not susceptible to compression by spasm of the trapezius, but is vulnerable where it penetrates the semispinalis capitis muscle. Pain alone is not likely to be the result of compression of a sensory nerve; experimental compression of a sensory nerve; experimental compression typically induces paresthesia or dysesthesia (MacKenzie et al, 1975). As noted above, tenderness of the greater occipital nerve is common to patients with headache of diverse causes and has no specificity in this syndrome. Referred pain to the occiput through compression of C2 or other mechanisms has often been designated occipital neuralgia (Dugan et al, 1962; Graff-Radford et al, 1986), which has led to the widespread belief that the boundaries of this disorder are vague.
Hammond and Danta (1978) and Bogduk (1980) have reviewed the literature on this condition and note that migraine is a common cause of jabbing pain in the occiput. In Raskin’s view, greater occipital neuralgia is nearly always secondary to trauma to the nerve or is a manifestation of postherpetic neuralgia. Zoster sine herpete may be the cause of otherwise obscure occipital burning pain with or without superimposed "pins and needles" discomfort. Lancinating, icepick-like pain is another common presenting complaint. Hypesthesia in the dermatome supplied by the greater occipital nerve is invariably present and the use of repeated local anesthetic blocks containing a suspension of betamethasone (6 mg) has led to resolution for most patients. Carbamazepine and indomethacin have been useful to those who have not been responsive to serial steroid blocks. Raskin has never resorted to neurectomy or removal of the C2 root ganglion.

Greater Occipital Nerve Block Technique
The nerve is identified at its point of entry to the scalp, along the superior muchal line midway between the mastoid process and the occipital protuberance (Figure 36.20). The patient will report pain upon compression: the point at which maximal tenderness is elicited can be used as the injection site. The scalp is cleansed with an alcohol swab; 6 mg betamethasone (1 ml) is drawn into a syringe containing 1 ml 2 percent lidocaine. A 25-gauge 5/8-inch needle is used for the block. The needle is directed toward the occiput until bony resistance is felt, thus ensuring that the subarachnoid space is not entered. About 0.6 ml is injected; the type of the needle is then withdrawn to just under the skin and redirected about 5 degrees laterally and then again medially, to deposit about 0.6 ml into each site to ensure a successful block. On completion of the injection, the injected area is massaged and compressed to spread the steroid suspension so that at least some of it bathes the nerve trunk. Hypesthesia should appear within 1 to 2 minutes, extending forward on the scalp to the interaural line.